In a medium bowl, combine ground beef, onion soup seasoning, Worcestershire sauce and salt. Allow to marinate for at least 1h, making sure to bring it to room temperature before cooking.

In a large fry pan, heat oil over medium-high heat. Add sliced onions, season with salt and toss to coat in oil. Add beef broth, reduce heat to low and cook for approx. 45 min., stirring occasionally, until onions are brown and caramelized.